Atmospheric Sb in the Arctic during the past 16,000 years: Responses to climate change and human impacts

Abstract. Anthropogenic climate change has altered many ecosystem processes in the Arctic tundra and may have resulted in unprecedented fire activity. Evaluating the significance of recent fires requires knowledge from the paleo-fire record because observational data in the Arctic span only several decades, much shorter than the natural fire rotation in Arctic tundra regions. Here we report results of charcoal analysis on lake sediments from four Alaskan lakes to infer the broad spatial and temporal patterns of tundra fire occurrence over the past 35 000 years. Background charcoal accumulation rates are low in all records (range = 0–0.05 pieces cm-2 year-1), suggesting minimal biomass burning across our study areas. Charcoal peak analysis reveals that the mean fire return interval (FRI; years between consecutive fire events) ranged from 1648 to 6045 years at our sites, and that the most recent fire events occurred from 882 to 7031 years ago, except for the CE 2007 Anaktuvuk River Fire. These mean FRI estimates are longer than the fire rotation periods estimated for the past 63 years in the areas surrounding three of the four study lakes. This result suggests that the frequency of tundra burning was higher over the recent past compared to the late Quaternary in some tundra regions. However, the ranges of FRI estimates from our paleo-fire records overlap with the expected values based on fire-rotation-period estimates from the observational fire data, and thus quantitative differences are not significant. Together with previous tundra-fire reconstructions, these data suggest that the rate of tundra burning was spatially variable and that fires were extremely rare in our study areas throughout the late Quaternary. Given the rarity of tundra burning over multiple millennia in our study areas and the pronounced effects of fire on tundra ecosystem processes such as carbon cycling, dramatic tundra ecosystem changes are expected if anthropogenic climate change leads to more frequent tundra fires.

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Early Holocene cold snaps and their expression in the moraine record of the Eastern European Alps

10.5194/cp-2021-54 ◽

2021 ◽

Author(s):

Sandra M. Braumann ◽

Joerg M. Schaefer ◽

Stephanie M. Neuhuber ◽

Christopher Lüthgens ◽

Alan J. Hidy ◽

...

Keyword(s):

Climate Change ◽

Arctic Region ◽

Climate System ◽

Early Holocene ◽

Ice Age ◽

The Arctic ◽

European Alps ◽

Eastern European ◽

Exposure Dating ◽

The Past

Abstract. Glaciers preserve climate variations in their geological and geomorphological records, which makes them prime candidates for climate reconstructions. Investigating the glacier-climate system over the past millennia is particularly relevant because, first, the amplitude and frequency of natural climate variability during the Holocene provides the climatic context against which modern, human-induced climate change must be assessed. Second, the transition from the last glacial to the current interglacial promises important insights into the climate system during warming, which is of particular interest with respect to ongoing climate change. Evidence of stable ice margin positions that record cooling during the past 12 ka are preserved in two glaciated valleys of the Silvretta Massif in the Eastern European Alps, the Jamtal (JAM) and the Laraintal (LAR). We mapped and dated moraines in these catchments including historical ridges using Beryllium-10 Surface Exposure Dating (10Be SED) techniques, and correlate resulting moraine formation intervals with climate proxy records to evaluate the spatial and temporal scale of these cold phases. The new geochronologies indicate two moraine formation intervals (MFI) during the Early Holocene (EH): 10.8 ± 0.7 ka (n = 9) and 11.2 ± 0.8 ka (n = 12). Boulder ages along historical moraines (n = 6) imply at least two glacier advances during the Little Ice Age (LIA; c. 1250–1850 CE), around 1300 CE and in the second half of the 18th century. An earlier advance to the same position may have occurred around 500 CE. The Jamtal and Laraintal moraine chronologies provide evidence that millennial scale EH warming was superimposed by centennial scale cooling. The timing of EH moraine formation is contemporaneous with brief temperature drops identified in local and regional paleoproxy records, most prominently with the Preboreal Oscillation (PBO), and is consistent with moraine deposition in other catchments in the European Alps, and in the Arctic region. This consistency points to cooling beyond the local scale and therefore a regional or even hemispheric climate driver. Freshwater input sourced from the Laurentide Ice Sheet (LIS), which changed circulation patterns in the North Atlantic, is a plausible explanation for EH cooling and moraine formation in the Nordic region and in Europe.

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Multi—Proxy Reconstructions of Climate Change and Human Impacts Over the Past 7000 Years From an Archive of Continental Shelf Sediments off Eastern Hainan Island, China

Frontiers in Earth Science ◽

10.3389/feart.2021.663634 ◽

2021 ◽

Vol 9 ◽

Author(s):

Chao Huang ◽

Deming Kong ◽

Fajin Chen ◽

Jianfang Hu ◽

Peng Wang ◽

...

Keyword(s):

Climate Change ◽

High Resolution ◽

Human Impacts ◽

Hainan Island ◽

Dominant Factor ◽

Environment Interaction ◽

Human Environment ◽

The Past ◽

The North ◽

Proxy Reconstructions

Abrupt climatic events and the history of human activities on Hainan Island are poorly understood, due to the lack of high-resolution records. We present high-resolution multiproxy records from the coastal shelf off eastern Hainan Island in China to investigate abrupt climate change and regional human–environment interaction over the last 7,000 years. A prominent climatic anomaly occurred during 5,400–4,900 cal yr BP. This abrupt monsoon failure has been detected in various paleoclimatic records from monsoonal regions. Anomalous summer monsoon intensity during 5,400–4,900 cal yr BP is probably driven by solar variability, ENSO activity and ice-rafting events in the North Atlantic. Over the past 1,500 years, with the growing population and progress in production technology, human activity has increasingly become the dominant factor controlling the natural environment of Hainan Island.

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CLIMATE CHANGE A REPERCUSSION OF HUMAN INDUCED SYSTEMS

International Journal of Advanced Research ◽

10.21474/ijar01/13431 ◽

2021 ◽

Vol 9 (09) ◽

pp. 449-452

Author(s):

Shweta Chand ◽

Keyword(s):

Climate Change ◽

Greenhouse Gases ◽

Temperature Rise ◽

Large Scale ◽

Crop Yields ◽

Heat Waves ◽

Human Impacts ◽

World Health ◽

The Arctic ◽

Weather Extremes

Climate change includes both the global warming driven by human emissions of greenhouse gases, and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century, humans have had unprecedented impact on Earths climate system and caused change on a global scale.The largest driver of warming is the emission of greenhouse gases, of which more than 90% are carbon dioxide and methane. Fossil fuel burning (coal, oil, and gas) for energy consumption is the main source of these emissions, with additional contributions from agriculture, deforestation, and industrial processes. The human cause of climate change is not disputed by any scientific body of national or international standing. Temperature rise is accelerated or tempered by climate feedbacks, such as loss of sunlight-reflecting snow and ice cover, increased water vapour (a greenhouse gas itself), and changes to land and ocean carbon sinks.Temperature rise on land is about twice the global average increase, leading to desert expansion and more common heat waves and wildfires. Increasing rates of evaporation cause more intense storms and weather extremes. Temperature rise is amplified in the Arctic, where it has contributed to melting permafrost and the retreat of glaciers and sea ice. Additional warming also increases the risk of triggering critical thresholds called tipping points. Impacts on ecosystems include the relocation or extinction of many species as their environment changes, most immediately in coral reefs, mountains, and the Arctic. Human impacts include undernutrition and hunger from reduced crop yields, declining fish stocks, increases in vector-borne diseases, potentially severe economic impacts, increased global economic inequality, more people living in uninhabitable climate zones, and increased migration.Effects such as these have led the World Health Organization to declare climate change the greatest threat to global health in the 21st century. Even if efforts to minimize future warming are successful, some effects will continue for centuries, including rising sea levels, rising ocean temperatures, and ocean acidification.

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BioDiv-Support: scenario-based decision support tool for policy planning and adaptation to future challenges in biodiversity and ecosystem services

10.5194/egusphere-egu21-14412 ◽

2021 ◽

Author(s):

Camilla Andersson ◽

Keyword(s):

Climate Change ◽

Air Pollution ◽

Ecosystem Services ◽

Management Practices ◽

Human Impacts ◽

Future Climate ◽

The Arctic ◽

Future Climate Change ◽

Local Stakeholders ◽

The Impact

Biodiversity includes any type of living variation, from the ecosystem level to genetic variation within organisms. The greatest threats to biodiversity is climate change, destruction of habitats and other human activities. High-altitude mountain regions are pristine environments, with historically small impacts from air pollution, but at risk of being disproportionately impacted by climate change. We focus on three mountainous regions: the Scandinavian Mountains, the Guadarrama Mountains in Spain, and the Pyrenees in France, Andorra and Spain. We study the impact of drivers of change of biodiversity such as future climate change, increased incidences of wild fires, emissions from new shipping routes in the Arctic as ice sheets are melting, human impacts on land use and management practices (such as reindeer grazing) and air pollution.We simulate future climate change using WRF and a convective permitting climate model, HARMONIE-Climate, with a spatial resolution of 3km. The high resolution strongly improves the representation of precipitation compared to coarser scale simulations (Lind et al., 2020). We use these simulations to develop future scenarios of air pollution load, using two well established chemistry transport models (MATCH and CHIMERE; Mar&#233;cal et al., 2015). These climate and air pollution scenarios are subsequently used, together with management scenarios, to develop scenarios for biodiversity and ecosystem services. These scenarios are developed applying a process-based dynamic vegetation and biogeochemistry model, LPJ-GUESS (Smith et al., 2014).&#160;The scenarios, representing mid-21st century, will be made available through a web-based planning tool, where local stakeholders in each region can explore the project results to understand how scenarios of climate change, air pollution and policy development will affect these ecosystems. Local stakeholders are involved throughout the project, such as reindeer herder communities, regional county boards and national authorities, and in a time of changing climate and a global pandemic we have learned the necessity for flexibility in such interactions.&#160;ReferencesLind et al. 2020., Climate Dynamics 55, 1893-1912.Mar&#233;cal et al., 2015. Geosci. Mod. Dev. 8, 2777-2813.Smith et al. 2014 Biogeosciences 11, 2027-2054.

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Regional impacts of climate change in the Arctic and Antarctic

Annals of Glaciology ◽

10.3189/1998aog27-1-543-552 ◽

1998 ◽

Vol 27 ◽

pp. 543-552 ◽

Cited By ~ 24

Author(s):

Gunter Weller

Keyword(s):

Climate Change ◽

Sea Ice ◽

Climate Impacts ◽

Indigenous Populations ◽

The Arctic ◽

Future Climate Change ◽

Greenhouse Warming ◽

Polar Regions ◽

Sea Ice Extent ◽

The Past

Regional assessments of impacts due to global climate change are a high priority in the international programs on global-change research. in the polar regions, climate models indicate an amplification of global greenhouse warming, but there are large differences between the results of various models, and uncertainties about the magnitude and timing of the expected changes. Also, the observed high-latitude climate trends over the past few decades are much more regional and patchy than predicted by the models. As a first step in assessing possible climate impacts, model results are compared with observations of changes in temperature, precipitation, sea-ice extent, the permafrost regime and other cryospheric parameters. While considerable uncertainties remain in the long-term prediction of change, there is some agreement between model results and observed trends by season on shorter time-scales, The warming observed over the land masses of the Arctic over the past few decades is matched by corresponding observed decreases in snow cover the glacier mass, balances, by thawing of the permafrost, and to a lesser degree by reductions in sea-ice extent. in Antarctica, warming in the Antarctic Peninsula and Ross Sea regions is associated with large decreases in ice-shelf areas and reduced ice thicknesses on the lakes in the McMurdo Dry Valleys. Major future impacts due to global greenhouse warming are likely to include permafrost thawing on and and its consequences for ecosystems and humans; changes in the productivity of marine ecosystems in the Arctic and Southern Ocean: economic impacts on fisheries, petroleum and other human activities; and social impacts on northern indigenous populations. Some of these impacts will have positive ramifications, but most are likely to be detrimental. While uncertainties exist about the future, climate change in the polar regions during the past few decades can be shown to have had major impacts already which will become much mole pronounced if present trends continue.

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Paleodust Insights into Dust Impacts on Climate

Journal of Climate ◽

10.1175/jcli-d-18-0742.1 ◽

2019 ◽

Vol 32 (22) ◽

pp. 7897-7913 ◽

Cited By ~ 6

Author(s):

Samuel Albani ◽

Natalie M. Mahowald

Keyword(s):

Climate Change ◽

Land Use Changes ◽

West African Monsoon ◽

Informed Choice ◽

West African ◽

The Arctic ◽

Model Parameters ◽

Size Distributions ◽

The Past ◽

Dust Load

Abstract Mineral dust acts both as a tracer and a forcing agent of climate change. Past dust variability, imprinted in paleodust records from natural archives, offers the unique opportunity to reconstruct the global dust cycle within a range of possibilities that plausibly encompass future variations in response to climate change and land-cover and land-use changes. Dust itself has direct and indirect feedbacks on the climate system, through impacts on the atmosphere radiative budget and the carbon cycle. Starting from well-constrained reconstructions of the present and past dust cycle, we focus on quantifying dust direct impacts on the atmospheric radiation. We discuss the intrinsic effects of dust onto climate, and how changes in the global dust budget and surface conditions modulate the effective impacts on surface temperatures and precipitation. Most notably, the presence of dust tends to enhance the West African monsoon and warm the Arctic. We also highlight how different choices in terms of dust optical properties and size distributions may yield opposite results, and what are the observational constraints we can use to make an informed choice of model parameters. Finally, we discuss how dust variability might have influenced ongoing climate transitions in the past. In particular we found that a reduction in dust load, along with a reduced cryosphere cover, acted to offset Arctic warming during the deglaciation, potentially playing a role in shaping the Northern Hemisphere deglacial dynamics.

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Human impacts, climate change, and aquatic ecosystem response during the past 2000 yr at Lake Wandakara, Uganda

Quaternary Research ◽

10.1016/j.yqres.2009.06.008 ◽

2009 ◽

Vol 72 (3) ◽

pp. 315-324 ◽

Cited By ~ 42

Author(s):

James M. Russell ◽

S.J. McCoy ◽

D. Verschuren ◽

I. Bessems ◽

Y. Huang

Keyword(s):

Climate Change ◽

Human Activities ◽

Human Impacts ◽

Organic Geochemistry ◽

Abundance Ratio ◽

Terrestrial Vegetation ◽

The Past ◽

Leaf Waxes ◽

Hydrogen Isotope Ratios ◽

Abrupt Shifts

AbstractAnalyses of carbon and hydrogen isotope ratios of terrestrial leaf waxes and the carbon and nitrogen abundance, ratio, and isotopic composition of bulk sediments from Lake Wandakara, a crater lake in western Uganda, East Africa, document human and climatic controls on the aquatic system and on the surrounding terrestrial vegetation during the past two millennia. Our data indicate that Wandakara was a relatively stable, productive lake surrounded by C3 vegetation from AD 70 to 1000. Abrupt changes in the δ13C of terrestrial leaf waxes indicate a series of abrupt shifts in the relative abundance of C3 and C4 vegetation caused by a combination of climate change and human activities around Wandakara beginning at AD 1000. Abrupt shifts in bulk sediment organic geochemistry, particularly C/N ratios and δ15N, indicate that human activities at this time caused permanent changes in the limnology of Lake Wandakara, including eutrophication. Our results suggest that the biogeochemistry of Lake Wandakara was more sensitive to shifting human impacts than to climate variations during the past millennium, highlighting the importance of understanding the intensity of pre-colonial human impacts on Africa's aquatic ecosystems.

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Biological response to climate change in the Arctic Ocean: the view from the past

arktos ◽

10.1007/s41063-015-0019-3 ◽

2015 ◽

Vol 1 (1) ◽

Cited By ~ 8

Author(s):

Thomas M. Cronin ◽

Matthew A. Cronin

Keyword(s):

Climate Change ◽

Arctic Ocean ◽

Biological Response ◽

The Arctic ◽

The Past ◽

The Arctic Ocean

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Early Holocene cold snaps and their expression in the moraine record of the eastern European Alps

Climate of the Past ◽

10.5194/cp-17-2451-2021 ◽

2021 ◽

Vol 17 (6) ◽

pp. 2451-2479

Author(s):

Sandra M. Braumann ◽

Joerg M. Schaefer ◽

Stephanie M. Neuhuber ◽

Christopher Lüthgens ◽

Alan J. Hidy ◽

...

Keyword(s):

Climate Change ◽

Arctic Region ◽

Climate System ◽

Early Holocene ◽

Ice Age ◽

The Arctic ◽

European Alps ◽

Eastern European ◽

Exposure Dating ◽

The Past

Abstract. Glaciers preserve climate variations in their geological and geomorphological records, which makes them prime candidates for climate reconstructions. Investigating the glacier–climate system over the past millennia is particularly relevant first because the amplitude and frequency of natural climate variability during the Holocene provides the climatic context against which modern, human-induced climate change must be assessed. Second, the transition from the last glacial to the current interglacial promises important insights into the climate system during warming, which is of particular interest with respect to ongoing climate change. Evidence of stable ice margin positions that record cooling during the past 12 kyr are preserved in two glaciated valleys of the Silvretta Massif in the eastern European Alps, the Jamtal (JAM) and the Laraintal (LAR). We mapped and dated moraines in these catchments including historical ridges using beryllium-10 surface exposure dating (10Be SED) techniques and correlate resulting moraine formation intervals with climate proxy records to evaluate the spatial and temporal scale of these cold phases. The new geochronologies indicate the formation of moraines during the early Holocene (EH), ca. 11.0 ± 0.7 ka (n = 19). Boulder ages along historical moraines (n = 6) suggest at least two glacier advances during the Little Ice Age (LIA; ca. 1250–1850 CE) around 1300 CE and in the second half of the 18th century. An earlier advance to the same position may have occurred around 500 CE. The Jamtal and Laraintal moraine chronologies provide evidence that millennial-scale EH warming was superimposed by centennial-scale cooling. The timing of EH moraine formation coincides with brief temperature drops identified in local and regional paleoproxy records, most prominently with the Preboreal Oscillation (PBO) and is consistent with moraine deposition in other catchments in the European Alps and in the Arctic region. This consistency points to cooling beyond the local scale and therefore a regional or even hemispheric climate driver. Freshwater input sourced from the Laurentide Ice Sheet (LIS), which changed circulation patterns in the North Atlantic, is a plausible explanation for EH cooling and moraine formation in the Nordic region and in Europe.

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